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diff --git a/man/sd_journal_stream_fd.xml b/man/sd_journal_stream_fd.xml new file mode 100644 index 0000000..af2234e --- /dev/null +++ b/man/sd_journal_stream_fd.xml @@ -0,0 +1,146 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> +<!-- SPDX-License-Identifier: LGPL-2.1-or-later --> + +<refentry id="sd_journal_stream_fd" xmlns:xi="http://www.w3.org/2001/XInclude"> + + <refentryinfo> + <title>sd_journal_stream_fd</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>sd_journal_stream_fd</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + + <refnamediv> + <refname>sd_journal_stream_fd</refname> + <refpurpose>Create log stream file descriptor to the journal</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> + + <funcprototype> + <funcdef>int <function>sd_journal_stream_fd</function></funcdef> + <paramdef>const char *<parameter>identifier</parameter></paramdef> + <paramdef>int <parameter>priority</parameter></paramdef> + <paramdef>int <parameter>level_prefix</parameter></paramdef> + </funcprototype> + + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para><function>sd_journal_stream_fd()</function> may be used to + create a log stream file descriptor. Log messages written to this + file descriptor as simple newline-separated text strings are + written to the journal. This file descriptor can be used + internally by applications or be made standard output or standard + error of other processes executed.</para> + + <para><function>sd_journal_stream_fd()</function> takes a short + program identifier string as first argument, which will be written + to the journal as SYSLOG_IDENTIFIER= field for each log entry + (see + <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> + for more information). The second argument shall be the default + priority level for all messages. The priority level is one of + <constant>LOG_EMERG</constant>, <constant>LOG_ALERT</constant>, + <constant>LOG_CRIT</constant>, <constant>LOG_ERR</constant>, + <constant>LOG_WARNING</constant>, <constant>LOG_NOTICE</constant>, + <constant>LOG_INFO</constant>, <constant>LOG_DEBUG</constant>, as + defined in <filename>syslog.h</filename>, see + <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> + for details. The third argument is a boolean: if true kernel-style + log level prefixes (such as <constant>SD_WARNING</constant>) are + interpreted, see + <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry> + for more information.</para> + + <para>It is recommended that applications log UTF-8 messages only + with this API, but this is not enforced.</para> + + <para>Each invocation of <function>sd_journal_stream_fd()</function> allocates a new log stream file descriptor, + that is not shared with prior or later invocations. The file descriptor is write-only (its reading direction is + shut down), and <constant>O_NONBLOCK</constant> is turned off initially.</para> + </refsect1> + + <refsect1> + <title>Return Value</title> + + <para>The call returns a valid write-only file descriptor on + success or a negative errno-style error code.</para> + </refsect1> + + <refsect1> + <title>Signal safety</title> + + <para><function>sd_journal_stream_fd()</function> is "async signal safe" in the meaning of <citerefentry + project='man-pages'><refentrytitle>signal-safety</refentrytitle><manvolnum>7</manvolnum></citerefentry>. + </para> + </refsect1> + + <refsect1> + <title>Notes</title> + + <xi:include href="threads-aware.xml" xpointer="safe"/> + + <xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/> + </refsect1> + + <refsect1> + <title>Examples</title> + + <para>Creating a log stream suitable for + <citerefentry project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>:</para> + + <programlisting>#include <syslog.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#include <systemd/sd-journal.h> +#include <systemd/sd-daemon.h> + +int main(int argc, char *argv[]) { + int fd; + FILE *log; + fd = sd_journal_stream_fd("test", LOG_INFO, 1); + if (fd < 0) { + fprintf(stderr, "Failed to create stream fd: %s\n", strerror(-fd)); + return 1; + } + log = fdopen(fd, "w"); + if (!log) { + fprintf(stderr, "Failed to create file object: %m\n"); + close(fd); + return 1; + } + fprintf(log, "Hello World!\n"); + fprintf(log, SD_WARNING "This is a warning!\n"); + fclose(log); + return 0; +}</programlisting> + + </refsect1> + + <refsect1> + <title>See Also</title> + + <para> + <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>fprintf</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |